How Can Premature Childbirth Be Prevented?

Hello I m 27 weeks pregnant with a girl and I m scared of early birth I have been to labor and delivery at my hospital and they say my cervix is looking good but what are some things to look for? My belly already dropped which I know isn t a good thing this earmy but what other symptoms do I need to look out for? Is there anything I can do not to go into early labor?